Relay state determination device, relay state determination system, relay state determination method, and non-transitory computer readable medium

ABSTRACT

A relay state determination device according to the present invention includes: a voltage value acquisition unit that measures every moment a detected voltage detected from two ends of a shunt resistor; a voltage value difference calculation unit that calculates a voltage value difference between a first voltage value of when the detected voltage becomes minimum by an armature starting displacement after a primary-side switch is turned off and a second voltage value of when secondary-side contacts are opened; and a state determination unit that determines that a relay has deteriorated when the voltage value difference falls below a predetermined threshold value.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of International Application No. PCT/JP2019/045184, with an International filing date of Nov. 19, 2019, which claims priority of Japanese Patent Application No. 2018-237585 filed on Dec. 19, 2018, the entire content of which is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a relay state determination device, a relay state determination system, a relay state determination method, and a non-transitory computer readable medium, and relates to, for example, a relay state determination device, a relay state determination system, a relay state determination method, and a non-transitory computer readable medium which can determine whether or not there is deterioration in a relay of a type that opens and closes a contact on a secondary side by turning on and off energization to a coil on a primary side.

BACKGROUND ART

Conventionally, as this type of relay state determination device, for example, as disclosed in JP 2013-89603 A, there is known a device that measures a maximum value of current flowing through an operation coil (actuating coil) on the primary side provided in a relay when the relay is turned off, and determines that the relay has deteriorated when the maximum value falls below a predetermined threshold value.

SUMMARY OF THE INVENTION

However, Patent Document 1 (JP 2013-89603 A) has a problem that, if the relay is a multipole type, deterioration of each individual pole is difficult to be determined.

Therefore, an object of the present invention is to provide a relay state determination device, a relay state determination system, a relay state determination method, and a program which can determine the deterioration of each individual pole in a relay.

In order to solve the above-mentioned problem, a relay state determination device of the present disclosure that determines whether or not a relay has deteriorated,

-   -   the relay includes:     -   a primary-side switch, an operation coil, and a shunt resistor         that are connected in series to a primary-side power supply;     -   a diode connected in parallel to a series connection of the         operation coil and the shunt resistor in a direction in which         current due to a counter electromotive force of the operation         coil flows to the shunt resistor when the primary-side switch is         turned off; and     -   an armature that opens and closes at least a pair of         secondary-side contacts in response to on and off of the         primary-side switch, the armature being configured to be         displaced relative to the operation coil by an electromagnetic         force generated by the operation coil when the primary-side         switch is turned on and to bring one of the secondary-side         contacts into contact with an other of the secondary-side         contacts while being deflected by a certain push-in amount,     -   the relay state determination device comprises:     -   a voltage value acquisition unit that measures every moment a         detected voltage detected from two ends of the shunt resistor;     -   a voltage value difference calculation unit that calculates a         voltage value difference between a first voltage value of when         the detected voltage becomes minimum by the armature starting         displacement after the primary-side switch is turned off and a         second voltage value of when the secondary-side contacts are         opened; and     -   a state determination unit that determines that the relay has         deteriorated when the voltage value difference falls below a         predetermined threshold value.

In another aspect, a relay state determination system of the present disclosure comprises:

-   -   a relay that includes a primary-side switch, an operation coil,         and a shunt resistor that are connected in series to a         primary-side power supply,     -   a diode connected in parallel to a series connection of the         operation coil and the shunt resistor in a direction in which         current due to a counter electromotive force of the operation         coil flows to the shunt resistor when the primary-side switch is         turned off, and     -   an armature that opens and closes at least a pair of         secondary-side contacts in response to on and off of the         primary-side switch, the armature being configured to be         displaced relative to the operation coil by an electromagnetic         force generated by the operation coil when the primary-side         switch is turned on and to bring one of the secondary-side         contacts into contact with an other of the secondary-side         contacts while being deflected by a certain push-in amount;     -   a first voltmeter that measures a detected voltage detected from         two ends of the shunt resistor;     -   a second voltmeter that measures a voltage between the pair of         secondary-side contacts of the relay; and     -   a relay state determination device communicably connected to the         first voltmeter and the second voltmeter,     -   wherein the relay state determination device includes:     -   a voltage value acquisition unit that measures every moment a         detected voltage detected from the two ends of the shunt         resistor;     -   a voltage value difference calculation unit that calculates a         voltage value difference between a first voltage value of when         the detected voltage becomes minimum by the armature starting         displacement after the primary-side switch is turned off and a         second voltage value of when the secondary-side contacts are         opened; and     -   a state determination unit that determines that the relay has         deteriorated when the voltage value difference falls below a         predetermined threshold value.

In another aspect, a relay state determination method of the present disclosure that determines whether or not deterioration has occurred in a relay includes:

-   -   a primary-side switch, an operation coil, and a shunt resistor         that are connected in series to a primary-side power supply;     -   a diode connected in parallel to a series connection of the         operation coil and the shunt resistor in a direction in which         current due to a counter electromotive force of the operation         coil flows to the shunt resistor when the primary-side switch is         turned off; and     -   an armature that opens and closes at least a pair of         secondary-side contacts in response to on and off of the         primary-side switch, the armature being configured to be         displaced relative to the operation coil by an electromagnetic         force generated by the operation coil when the primary-side         switch is turned on and to bring one of the secondary-side         contacts into contact with an other of the secondary-side         contacts while being deflected by a certain push-in amount,     -   the relay state determination method comprises:     -   measuring every moment a detected voltage detected from two ends         of the shunt resistor;     -   calculating a voltage value difference between a first voltage         value of when the detected voltage becomes minimum by the         armature starting displacement after the primary-side switch is         turned off and a second voltage value of when the secondary-side         contacts are opened; and     -   determining that the relay has deteriorated when the voltage         value difference falls below a predetermined threshold value.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is a diagram showing a schematic configuration of a relay state determination system according to an embodiment.

FIG. 2 is a diagram showing a block configuration of a relay state determination device included in the relay state determination system in FIG. 1 .

FIG. 3 is a flowchart explaining an operation of the relay state determination system in FIG. 1 .

FIG. 4A is a diagram showing a state in which a switch on a secondary side of the relay is “closed”. FIG. 4B is a diagram showing a state in which the switch on the secondary side of the relay is “opened”.

FIG. 5 is a diagram illustrating a voltage waveform.

FIG. 6 is a diagram showing a relationship between the RUS of the relay and the number of opening and closing times of the relay, for each of a plurality of samples.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present disclosure is described in detail with reference to the drawings.

(Schematic Configuration of Relay State Determination System 100)

FIG. 1 shows an overall configuration of a relay state determination system 100. As an example, the relay state determination system 100 determines whether or not a relay 4 has deteriorated. Here, “deterioration” of the relay 4 means that opening and closing of the relay 4 may not be normally operated. In other words, failure may have occurred. This is a state of the relay 4.

As shown in FIG. 1 , the relay state determination system 100 includes the relay 4, voltmeters 5 and 8, and a relay state determination device 10. The relay state determination system 100 further includes a direct current (DC) power supply 1, a switch device 2, a diode 3, a shunt resistor 9, an alternating current (AC) power supply 6, and a load 7.

As shown in FIG. 1 , the relay 4 is arranged across a primary-side circuit and a secondary-side circuit. The relay 4 includes an operation coil 4 a on a primary side and a switch 4 b on a secondary side. In addition, the switch 4 b on the secondary side has a pair of contacts (a first contact 4 b 1 and a second contact 4 b 2) in this example. The pair of contacts 4 b 1 and 4 b 2 are opened and closed by turning on and off the energization to the operation coil 4 a on the primary side.

As shown in FIG. 1 , in the primary-side circuit, a positive electrode terminal 1 p of the DC power supply 1 is connected to a one end 2 a of the switch device 2. An other end 2 b of the switch device 2 is connected to a cathode terminal 3 k of the diode 3. The other end 2 b of the switch device 2 is connected to a one end 4 a 1 of the operation coil 4 a. A negative electrode terminal 1 m of the DC power supply 1 is connected to an anode terminal 3 a of the diode 3. The negative electrode terminal 1 m of the DC power supply 1 is connected to a one end 9 a of the shunt resistor 9. An other end 9 b of the shunt resistor is connected to an other end 4 a 2 of the operation coil 4 a. The voltmeter 8 is connected in parallel to the shunt resistor 9. As a result, the voltmeter 8 can measure a voltage value between the two ends 9 a and 9 b of the shunt resistor 9.

As shown in FIG. 1 , in the secondary-side circuit, the first contact 4 b 1 of the switch 4 b is connected to a one end 6 a of the AC power supply 6 being a load power supply. An other end 6 b of the AC power supply 6 is connected to a one end 7 a of the load 7. An other end 7 b of the load 7 is connected to the second contact 4 b 2 of the switch 4 b. The voltmeter 5 is connected in parallel to the switch 4 b. Thus, the voltmeter 5 can measure a voltage value between the pair of contacts 4 b 1 and 4 b 2 of the relay 4.

The relay state determination device 10 is arranged separately from the primary-side circuit and the secondary-side circuit described above. As shown in FIG. 1 , the relay state determination device 10 is communicably connected to the voltmeters 5 and 8. The connection between the relay state determination device 10 and the voltmeters 5 and 8 may be wired or wireless. With this configuration, the relay state determination device 10 can receive voltage values, which are measurement results of the voltmeters 5 and 8, from the voltmeters 5 and 8. The relay state determination device 10 is communicably connected to the switch device 2. The connection between the relay state determination device 10 and the switch device 2 may be wired or wireless. With this configuration, the switch device 2 can notify the relay state determination device 10 of the off timing of the switch device 2.

The DC power supply 1 supplies a direct current to the operation coil 4 a in the relay 4. In this example, the switch device 2 is composed of a field effect transistor (FET), and is switched from an ON state to an OFF state or from the OFF state to the ON state according to a switch control signal from the outside (not illustrated). The switch device 2 transmits a signal indicating the switching timing to the relay state determination device 10. The switch device 2 may be composed of a semiconductor switch other than the FET or a mechanical switch. The diode 3 is arranged to protect the circuit from a counter electromotive voltage generated by the operation coil 4 a being an inductive load.

As described above, in the relay 4, the pair of contacts 4 b 1 and 4 b 2 on the secondary side is opened and closed by turning on and off the energization to the operation coil 4 a on the primary side. More specifically, when the switch device 2 is switched on, the energization from the DC power supply 1 to the operation coil 4 a is turned on. When the operation coil 4 a is energized, the relay 4 (more specifically, the switch 4 b) is closed. On the other hand, when the switch device 2 is switched off, the energization from the DC power supply 1 to the operation coil 4 a is turned off. When the operation coil 4 a is de-energized, the relay 4 (more specifically, the switch 4 b) is opened.

The switch 4 b in the relay 4 has the first contact 4 b 1 and the second contact 4 b 2. The voltmeter 5 measures the voltage value between the first contact 4 b 1 and the second contact 4 b 2. The voltmeter 5 transmits the measured voltage value as a signal to the relay state determination device 10. The AC power supply 6 supplies AC power to the load 7. Then, the load 7 consumes the supplied AC power and performs a predetermined operation.

(Operation of Relay)

FIG. 4A illustrates a state in which the switch device 2 is turned on and the switch 4 b of the relay 4 is “closed”. In this state, an armature 4A of the switch 4 b is displaced relative to the operation coil 4 a by electromagnetic force E1 generated by the operation coil 4 a. Specifically, the armature 4A rotates in a direction indicated by an arrow X1 around a supporting point SP against tensile force F1 of a coil spring 41, and brings the first contact 4 b 1 into contact with the second contact 4 b 2 while bending by a certain push-in amount Bx.

FIG. 4B illustrates a state in which the switch device 2 is turned off and the switch 4 b of the relay 4 is “opened”. In this state, the electromagnetic force E1 generated by the operation coil 4 a decreases, and as a result, the armature 4A of the switch 4 b rotates in a direction indicated by an arrow X2 around the supporting point SP by tensile force F2 of the coil spring 41. As a result, the pressure pressing the first contact 4 b 1 changes from a certain value to zero, and the first contact 4 b 1 is separated from the second contact 4 b 2. In this case, a counter electromotive voltage is generated in the operation coil 4 a, and current flowing through the operation coil 4 a flows back through the diode 3.

(Schematic Configuration of Relay State Determination Device 10)

Next, a configuration of the relay state determination device 10 is described. FIG. 2 illustrates a schematic configuration of the relay state determination device 10. In the present embodiment, the relay state determination device 10 determines whether the relay 4 described above has deteriorated. As illustrated in FIG. 2 , the relay state determination device 10 includes a signal reception unit 21, a voltage value acquisition unit 22, a display unit 23, an operation unit 24, a memory 25, a threshold value storage unit 26, a notification unit 27, and a processor 28.

In the relay state determination device 10, the processor 28 is communicably connected to the signal reception unit 21, the voltage value acquisition unit 22, the display unit 23, the operation unit 24, the memory 25, the threshold value storage unit 26, and the notification unit 27. With this configuration, the processor 28 controls the signal reception unit 21, the voltage value acquisition unit 22, the display unit 23, the operation unit 24, the memory 25, the threshold value storage unit 26, and the notification unit 27, and the respective units 21, 22, 23, 24, 25, 26, and 27 perform predetermined operations by the control.

The signal reception unit 21 transmits and receives a signal or data to and from an external terminal. For example, the signal reception unit 21 according to the present embodiment is communicably connected to the switch device 2. Therefore, the signal reception unit 21 receives, from the switch device 2, data indicating the timing at which the switch device 2 is turned to the OFF state, and the like.

The voltage value acquisition unit 22 transmits and receives a signal or data to and from the external terminal. For example, the voltage value acquisition unit 22 according to the present embodiment is communicably connected to the voltmeters 5 and 8. Therefore, the voltage value acquisition unit 22 receives (acquires) signals indicating the voltage values measured by the voltmeters 5 and 8 from the voltmeters 5 and 8.

The display unit 23 is a monitor that displays various images. The display unit 23 can visually display results of various types of analysis and the like performed in the processor 28. In addition, the display unit 23 can also visibly display predetermined information in response to an instruction from the user via the operation unit 24. For example, the display unit 23 may visibly display the information (data) stored in the memory 25 and the threshold value storage unit 26. Furthermore, the display unit 23 may visibly display a predetermined notification and the like. For example, a liquid crystal monitor or the like can be adopted as the display unit 23.

The operation unit (which can be understood as a threshold value input unit) 24 is a portion that receives a predetermined operation (instruction) from the user. For example, the operation unit 24 is constituted of a mouse, a keyboard, and others. Note that in the case in which a touch panel monitor is employed as the display unit 23, the display unit 23 has not only a display function but also a function as the operation unit 24.

The memory 25 stores various types of data. The memory 25 includes a random access memory (RAM), a read only memory (ROM), and others. For example, various programs used for such as the operation of the processor 28 are changeably stored in the memory 25. In addition, the memory 25 stores data (data indicating the switching timing) from the switch device 2 acquired by the signal reception unit 21, voltage value data from the voltmeters 5 and 8 acquired by the voltage value acquisition unit 22, and so on. The memory 25 may erase various types of stored data after a preset predetermined time period elapses after the storage.

The threshold value storage unit 26 stores a threshold value Th for determining whether or not the relay 4 has deteriorated. Here, the threshold value Th is determined (set) by the user based on such as an empirical rule. The threshold value Th stored in the threshold value storage unit 26 can be changed. For example, the operation unit 24 functions as the threshold value input unit for variably inputting the threshold value Th. The user inputs a desired threshold value Th to the operation unit 24. By this, the threshold value Th is stored (set) in the threshold value storage unit 26. Note that, in the case in which a threshold value Th′ is already stored in the threshold value storage unit 26, the threshold value Th′ is changed to the threshold value Th corresponding to the operation by the operation from the user via the operation unit 24. Note that the threshold value storage unit 26 may have a predetermined threshold value Th as a default.

The notification unit 27 notifies that the relay 4 has deteriorated based on an analysis result of the processor 28 described later. For example, in the case in which the notification unit 27 includes such as a speaker, the notification unit 27 outputs a predetermined sound. Furthermore, for example, in the case in which the notification unit 27 includes a member that outputs predetermined light, the notification unit 27 outputs the predetermined light. The display unit 23 can have the function of the notification unit 27, and in this case, predetermined information (information indicating deterioration of the relay 4) is displayed on the display unit 23 in a visually recognizable manner.

The processor 28 includes a central processing unit (CPU) in this example. For example, the processor 28 reads each program and each piece of data stored in the memory 25. In addition, the processor 28 controls each of the units 21 to 27 according to the read program to execute a predetermined operation (function). In addition, the processor 28 performs predetermined calculation, analysis, processing, and others in the processor 28 (blocks 28 a and 28 b configured by programs) according to the read program. Note that some or all of the functions executed by the processor 28 may be configured as hardware by one or a plurality of integrated circuits or the like.

As illustrated in FIG. 2 , the processor 28 according to the present embodiment includes, as functional blocks, an RUS calculation unit 28 a and a state determination unit 28 b programmed to realize predetermined operations. Note that the operation of each of the blocks 28 a and 28 b is described in detail in the description of the operation to be described later.

(Operation of Relay State Determination System 100)

Next, the operation of the relay state determination system 100 to determine whether or not the relay 4 has deteriorated is described with reference to a flowchart shown in FIG. 3 .

Referring to FIG. 3 , it is assumed that the switch device 2 is switched from the ON state to the OFF state (step S1). The switch device 2 notifies the relay state determination device 10 of the switching. The signal reception unit 21 of the relay state determination device 10 receives the notification.

Next, the voltmeter 8 measures a voltage between the two ends 9 a and 9 b of the shunt resistor 9 (step S2). The voltmeter 8 transmits a voltage value Va as the measurement result to the relay state determination device 10, and the voltage value acquisition unit 22 of the relay state determination device 10 receives the voltage value Va. The memory 25 stores the voltage value Va received by the voltage value acquisition unit 22. At this time, the voltmeter 8 is measuring every moment the voltage between the two ends 9 a and 9 b of the shunt resistor 9.

Note that FIG. 5 illustrates time changes of the voltage value Va between the two ends 9 a and 9 b of the shunt resistor 9 and a voltage value Vb between the first contact 4 b 1 and the second contact 4 b 2 in the switch 4 b, after the turn-off instruction to the relay 4 (after step S1 in FIG. 3 ). The vertical axis in FIG. 5 represents the voltage value (V), and the horizontal axis in FIG. 5 represents time (ms).

Next, the RUS calculation unit 28 a of the relay state determination device 10 acquires a voltage value V1 of when the voltage value Va decreases and becomes minimum by the armature 4A starting to be displaced in the direction indicated by the arrow X2 in FIG. 4B (step S3 in FIG. 3 ).

Next, the voltmeter 5 measures the voltage between the first contact 4 b 1 and the second contact 4 b 2 in the switch 4 b. Then, when the switch 4 b is opened (as indicated by a dotted circle D in FIG. 5 , which indicates the case in which the voltage value Vb suddenly decreases), the RUS calculation unit 28 a of the relay state determination device 10 acquires the voltage value Va measured by the voltmeter 8 as a second voltage value V2 (step S4 in FIG. 3 ).

Next, the RUS calculation unit 28 a as the voltage value difference calculation unit of the relay state determination device 10 calculates a voltage value difference VD between the voltage value V1 and the voltage value V2 (step S5).

Next, the RUS calculation unit 28 a of the relay state determination device 10 calculates the RUS by dividing the voltage value difference VD by a resistance value of the shunt resistor 9 (step S6).

Next, the RUS calculation unit 28 a transmits the RUS to the state determination unit 28 b. The state determination unit 28 b reads out the threshold value Th stored in the threshold value storage unit 26. Then, the state determination unit 28 b compares the RUS with the threshold value Th to determine whether or not the relay 4 has deteriorated (step S7).

Note that, as can be seen from the above, the RUS used in the comparison processing in step S7 is the RUS obtained in step S6. Further, the threshold value used in the comparison processing in step S7 is the threshold value Th preset in the threshold value storage unit 26 of the relay state determination device 10.

Still further, the threshold value Th is set by the user on the basis of an empirical rule or the like. FIG. 6 illustrates a relationship between the RUS and the number of opening and closing times of the contacts 4 b 1 and 4 b 2. The vertical axis in FIG. 6 is the RUS (μA), and the horizontal axis in FIG. 6 is the number of opening and closing times of the contacts 4 b 1 and 4 b 2. As illustrated in FIG. 6 , generally, as the number of opening and closing times of the relay 4 increases, the RUS gradually decreases. The user sets the threshold value Th on the basis of an empirical rule in consideration of the measurement result of the RUS illustrated in FIG. 6 , the usage status of the relay 4, the expected time point of the failure of the relay 4 (the time point at which the opening and closing of the relay 4 is expected not to operate normally), and the like. In the example of FIG. 6 , the threshold value Th is set to 100 μA. That is, in the example of FIG. 6 , the user considers the above factors, and determines that the relay 4 has deteriorated when the RUS of the relay 4 to be used falls below 100 μA.

In step S7 of FIG. 3 , specifically, the state determination unit 28 b determines whether or not the RUS has fallen below the threshold value Th. It is assumed that the state determination unit 28 b determines that the RUS is equal to the threshold value Th or more (“NO” in step S7). In this case, as illustrated in FIG. 3 , the relay state determination processing ends.

On the other hand, it is assumed that the state determination unit 28 b determines that the RUS has fallen below the threshold value Th (“YES” in step S7). In this case, the state determination unit 28 b controls the notification unit 27, and the notification unit 27 notifies that the relay 4 has deteriorated (step S8). Thereafter, the relay state determination processing ends.

(Effects)

As described in the prior art, if the relay is the multipole type, there is a problem that the deterioration of each individual pole is difficult to be determined. On the other hand, in the present embodiment, the RUS is calculated for each switch 4 b, that is, for each pole. Then, it is determined whether or not the RUS has fallen below the threshold value. As a result, the deterioration of each individual pole in the relay can be determined.

FIG. 6 shows a certain test data exemplifying the relationship between the RUS of the relay and the number of opening and closing times of the relay. Samples #1 to #5 shown in FIG. 6 are relays of the same type (model number) and have been tested under the same conditions. As can be seen from the experimental example of FIG. 6 , even in the relay of the same type (model number), the individual difference between the samples #1 to #5 is large regarding such as the RUS.

In consideration to this, in the present embodiment, the RUS calculation unit 28 a calculates the RUS for the relay 4. Then, the state determination unit 28 b compares the RUS with the threshold value Th to determine whether the relay 4 has deteriorated. Here, it is empirically known that the individual difference of the relay 4 is small for the RUS when the relay 4 has deteriorated. Therefore, according to the present embodiment, it is possible to accurately determine whether or not the relay 4 has deteriorated.

In addition, in the present embodiment, when it is determined that the RUS has fallen below the threshold value Th (“YES” in step S7), the notification unit 27 notifies that the relay 4 has deteriorated. Therefore, the user can quickly take measures such as replacing the relay 4.

Software (computer program) for causing a computer to execute the relay state determination method (FIG. 3 ) may be recorded in a recording medium that can store data in a non-transitory manner, such as a compact disc (CD), a digital versatile disc (DVD), or a flash memory. By installing the software recorded on the recording medium in an actual computer device such as a personal computer, a personal digital assistant (PDA), or a smartphone, the computer can be caused to execute the relay state determination method described above.

In addition, in the above-described embodiment, the processor 28 includes a CPU, but the present invention is not limited thereto. The processor 28 may include a logic circuit (integrated circuit) such as a programmable logic device (PLD) or a field programmable gate array (FPGA).

As described above, a relay state determination device of the present disclosure that determines whether or not a relay has deteriorated,

-   -   the relay includes:     -   a primary-side switch, an operation coil, and a shunt resistor         that are connected in series to a primary-side power supply;     -   a diode connected in parallel to a series connection of the         operation coil and the shunt resistor in a direction in which         current due to a counter electromotive force of the operation         coil flows to the shunt resistor when the primary-side switch is         turned off; and     -   an armature that opens and closes at least a pair of         secondary-side contacts in response to on and off of the         primary-side switch, the armature being configured to be         displaced relative to the operation coil by an electromagnetic         force generated by the operation coil when the primary-side         switch is turned on and to bring one of the secondary-side         contacts into contact with an other of the secondary-side         contacts while being deflected by a certain push-in amount,     -   the relay state determination device comprises:     -   a voltage value acquisition unit that measures every moment a         detected voltage detected from two ends of the shunt resistor;     -   a voltage value difference calculation unit that calculates a         voltage value difference between a first voltage value of when         the detected voltage becomes minimum by the armature starting         displacement after the primary-side switch is turned off and a         second voltage value of when the secondary-side contacts are         opened; and     -   a state determination unit that determines that the relay has         deteriorated when the voltage value difference falls below a         predetermined threshold value.

In the relay state determination device of the present disclosure, the voltage value acquisition unit measures every moment the detected voltage detected from two ends of the shunt resistor. The voltage value difference calculation unit calculates the voltage value difference between the first voltage value of when the detected voltage becomes minimum by the armature starting displacement after the primary-side switch is turned off and the second voltage value of when the secondary-side contacts are opened. The state determination unit determines that the relay has deteriorated when the voltage value difference falls below the predetermined threshold value. In this way, the deterioration for each secondary-side contact, that is, for each pole of the relay, can be determined. Therefore, the deterioration of each individual pole in the relay can be determined.

In the relay determination device of one embodiment, the state determination unit determines that the relay has deteriorated when a current value obtained by dividing the voltage value difference by a value of the shunt resistor falls below a predetermined threshold value.

In the present description, the phrase “the current value obtained by dividing the voltage value difference by the value of the shunt resistor, the voltage value difference being a value between the first voltage value of when the detected voltage becomes minimum by the armature starting displacement after the primary-side switch is turned off and the second voltage value of when the secondary-side contacts are opened” (this is referred to as “Reset Undershoot (RUS)), is a value of current flowing through the operation coil in a period until the pressure pressing the secondary-side movable contact changes from a certain value to zero. This corresponds to the push-in amount of the armature, and the decrease in the push-in amount indicates that the armature is deteriorated.

In the relay state determination device of the one embodiment, the state determination unit determines that the relay has deteriorated when the current value obtained by dividing the voltage value difference by the value of the shunt resistor falls below a predetermined threshold value. Therefore, the deterioration of the relay can be determined based on the current value (that is, the RUS).

In the relay state determination device of one embodiment, the relay state determination device further comprises a notification unit that notifies that the relay has deteriorated when it is determined that the voltage value difference or the current value obtained by dividing the voltage value difference by the value of the shunt resistor is less than a predetermined threshold value.

In the relay state determination device of the one embodiment, a user can recognize that the relay has deteriorated by receiving the notification. Therefore, the user can quickly take measures such as replacing the relay.

In another aspect, a relay state determination system of the present disclosure comprises:

-   -   a relay that includes a primary-side switch, an operation coil,         and a shunt resistor that are connected in series to a         primary-side power supply,     -   a diode connected in parallel to a series connection of the         operation coil and the shunt resistor in a direction in which         current due to a counter electromotive force of the operation         coil flows to the shunt resistor when the primary-side switch is         turned off, and     -   an armature that opens and closes at least a pair of         secondary-side contacts in response to on and off of the         primary-side switch, the armature being configured to be         displaced relative to the operation coil by an electromagnetic         force generated by the operation coil when the primary-side         switch is turned on and to bring one of the secondary-side         contacts into contact with an other of the secondary-side         contacts while being deflected by a certain push-in amount;     -   a first voltmeter that measures a detected voltage detected from         two ends of the shunt resistor;     -   a second voltmeter that measures a voltage between the pair of         secondary-side contacts of the relay; and     -   a relay state determination device communicably connected to the         first voltmeter and the second voltmeter,     -   wherein the relay state determination device includes:     -   a voltage value acquisition unit that measures every moment a         detected voltage detected from the two ends of the shunt         resistor;     -   a voltage value difference calculation unit that calculates a         voltage value difference between a first voltage value of when         the detected voltage becomes minimum by the armature starting         displacement after the primary-side switch is turned off and a         second voltage value of when the secondary-side contacts are         opened; and     -   a state determination unit that determines that the relay has         deteriorated when the voltage value difference falls below a         predetermined threshold value.

In the relay state determination system of the present disclosure, the deterioration of each individual pole in the relay can be determined.

In another aspect, a relay state determination method of the present disclosure that determines whether or not deterioration has occurred in a relay includes:

-   -   a primary-side switch, an operation coil, and a shunt resistor         that are connected in series to a primary-side power supply;     -   a diode connected in parallel to a series connection of the         operation coil and the shunt resistor in a direction in which         current due to a counter electromotive force of the operation         coil flows to the shunt resistor when the primary-side switch is         turned off; and     -   an armature that opens and closes at least a pair of         secondary-side contacts in response to on and off of the         primary-side switch, the armature being configured to be         displaced relative to the operation coil by an electromagnetic         force generated by the operation coil when the primary-side         switch is turned on and to bring one of the secondary-side         contacts into contact with an other of the secondary-side         contacts while being deflected by a certain push-in amount,     -   the relay state determination method comprises:     -   measuring every moment a detected voltage detected from two ends         of the shunt resistor;     -   calculating a voltage value difference between a first voltage         value of when the detected voltage becomes minimum by the         armature starting displacement after the primary-side switch is         turned off and a second voltage value of when the secondary-side         contacts are opened; and     -   determining that the relay has deteriorated when the voltage         value difference falls below a predetermined threshold value.

In the relay state determination method of the present disclosure, the deterioration of each individual pole in the relay can be determined.

In yet another aspect, a non-transitory computer readable medium of the present disclosure is the non-transitory computer readable medium configured to cause a computer to execute the relay state determination method.

The relay state determination method can be performed by causing a computer to execute the non-transitory computer readable medium of the present disclosure.

The above embodiments are illustrative, and various modifications can be made without departing from the scope of the present invention. It is to be noted that the various embodiments described above can be appreciated individually within each embodiment, but the embodiments can be combined together. It is also to be noted that the various features in different embodiments can be appreciated individually by its own, but the features in different embodiments can be combined. 

The invention claimed is:
 1. A relay state determination device that determines whether or not a relay has deteriorated, the relay including: a primary-side switch, an operation coil, and a shunt resistor that are connected in series to a primary-side power supply; a diode connected in parallel to a series connection of the operation coil and the shunt resistor in a direction in which current due to a counter electromotive force of the operation coil flows to the shunt resistor when the primary-side switch is turned off; and an armature that opens and closes at least a pair of secondary-side contacts in response to on and off of the primary-side switch, the armature being configured to be displaced relative to the operation coil by an electromagnetic force generated by the operation coil when the primary-side switch is turned on and to bring one of the secondary-side contacts into contact with an other of the secondary-side contacts while being deflected by a certain push-in amount, the relay state determination device comprising: a voltage value acquisition unit that measures every moment a detected voltage detected from two ends of the shunt resistor; a voltage value difference calculation unit that calculates a voltage value difference between a first voltage value of when the detected voltage becomes minimum by the armature starting displacement after the primary-side switch is turned off and a second voltage value of when the secondary-side contacts are opened; and a state determination unit that determines that the relay has deteriorated when the voltage value difference falls below a predetermined threshold value.
 2. The relay state determination device according to claim 1, wherein the state determination unit determines that the relay has deteriorated when a current value obtained by dividing the voltage value difference by a value of the shunt resistor falls below a predetermined threshold value.
 3. The relay state determination device according to claim 1, further comprising a notification unit that notifies that the relay has deteriorated when it is determined that the voltage value difference or the current value obtained by dividing the voltage value difference by the value of the shunt resistor is less than a predetermined threshold value.
 4. A relay state determination system comprising: a relay that includes a primary-side switch, an operation coil, and a shunt resistor that are connected in series to a primary-side power supply, a diode connected in parallel to a series connection of the operation coil and the shunt resistor in a direction in which current due to a counter electromotive force of the operation coil flows to the shunt resistor when the primary-side switch is turned off, and an armature that opens and closes at least a pair of secondary-side contacts in response to on and off of the primary-side switch, the armature being configured to be displaced relative to the operation coil by an electromagnetic force generated by the operation coil when the primary-side switch is turned on and to bring one of the secondary-side contacts into contact with an other of the secondary-side contacts while being deflected by a certain push-in amount; a first voltmeter that measures a detected voltage detected from two ends of the shunt resistor; a second voltmeter that measures a voltage between the pair of secondary-side contacts of the relay; and a relay state determination device communicably connected to the first voltmeter and the second voltmeter, wherein the relay state determination device includes: a voltage value acquisition unit that measures every moment a detected voltage detected from the two ends of the shunt resistor; a voltage value difference calculation unit that calculates a voltage value difference between a first voltage value of when the detected voltage becomes minimum by the armature starting displacement after the primary-side switch is turned off and a second voltage value of when the secondary-side contacts are opened; and a state determination unit that determines that the relay has deteriorated when the voltage value difference falls below a predetermined threshold value.
 5. A relay state determination method that determines whether or not deterioration has occurred in a relay including: a primary-side switch, an operation coil, and a shunt resistor that are connected in series to a primary-side power supply; a diode connected in parallel to a series connection of the operation coil and the shunt resistor in a direction in which current due to a counter electromotive force of the operation coil flows to the shunt resistor when the primary-side switch is turned off; and an armature that opens and closes at least a pair of secondary-side contacts in response to on and off of the primary-side switch, the armature being configured to be displaced relative to the operation coil by an electromagnetic force generated by the operation coil when the primary-side switch is turned on and to bring one of the secondary-side contacts into contact with an other of the secondary-side contacts while being deflected by a certain push-in amount, the relay state determination method comprising: measuring every moment a detected voltage detected from two ends of the shunt resistor; calculating a voltage value difference between a first voltage value of when the detected voltage becomes minimum by the armature starting displacement after the primary-side switch is turned off and a second voltage value of when the secondary-side contacts are opened; and determining that the relay has deteriorated when the voltage value difference falls below a predetermined threshold value.
 6. A non-transitory computer readable medium configured to cause a computer to execute the relay state determination method according to claim
 5. 